From land to seabed: uncovering the fate of plastic in the ocean

, Navarrete Fernandez Teresa Magdalena, Morales-Caselles Carmen, Viejo Josue, Hernandez Ignacio, Gonzalez-Gordillo J Ignacio, Cózar Andrés.

From the estimated 4.8- 12.7 million MT of plastic litter that enters the ocean every year, only 0.3 million MT of it is floating on the surface, whereas the rest goes missing. The unbalances in the size distribution of floating plastics also supports the idea of an unquantified sink of litter in the ocean. The striking scarcity of millimetre-sized fragments on the sea surface has been explained by a combination of mechanisms diverting fragments into the water column and the seabed. However, the load of microplastic on the ocean floor at a large scale is unknown. In this study, we analyze the abundance of microplastics in 188 sediment samples from 45 sites in the Mediterranean Sea. By compiling a sufficiently extensive data sets, we found a sharp decrease in the microplastic concentrations with increasing distance from land sources. Although multiple environmental factors control the spatial distribution of microplastic on the seafloor, the distance to the main sources of mismanaged plastic waste was by far the main driver for the microplastic concentration at the macroscale.

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